Catalyst composition and preparation method of 1-butene

Abstract

The invention provides a catalyst composition and a preparation method of 1-butene. The catalyst composition comprises an organic titanium compound and an organic aluminum compound, the general formula of the organic titanium compound is Ti (OR1) 2 (OC2H4N (C2H4OH) 2) 2, wherein R1 is alkyl; the molar ratio of the organic titanium compound to the organic aluminum compound is 1: (1-20). On the basis of modification of steric hindrance of an active center of the catalyst and an electronic environment brought by the structure of the organic titanium compound, when the catalyst is subsequently used for preparing 1-butene through ethylene dimerization, the reaction induction period is shorter, and the selectivity of 1-butene is higher. Meanwhile, the cost of the catalyst is lower.

Description

Technical Field

[0001] This invention relates to the field of ethylene oligomerization into long-chain linear α-olefins, specifically to a catalyst composition and a method for preparing 1-butene. Background Technology

[0002] 1-Butene is a major comonomer in production line low-density polyethylene (LLDPE) and high-density polyethylene (HDPE). Its short, side-branched structure, acting as a binding molecule, provides stronger bonding between polyethylene flakes, significantly improving the tensile strength, impact strength, tear resistance, and other mechanical properties of polyethylene products. The main methods for industrial production of polymer-grade 1-butene include: the pyrolysis-mixing C4 separation process and the ethylene dimerization process.

[0003] On the one hand, in the traditional ethylene dimerization to 1-butene process, the multi-component catalysts used require complexation to form active intermediates, and this complexation process leads to an excessively long initial induction period. On the other hand, the catalysts commonly used in the ethylene dimerization to 1-butene process are relatively expensive.

[0004] For example, CN109225338A provides a recyclable liquid-phase ethylene selective dimerization heterogeneous catalyst and its preparation method. This technology describes the following: Ni-UMOFs, Co-UMOFs, and NiCo-UMOFs catalysts, in the presence of diethylaluminum chloride co-catalyst (Al:Ni = 500), react at 25°C and 1 MPa pressure for 1 h, achieving a maximum activity of 1.55 x 10⁻⁶. 5 g / mol·h -1 The catalyst can be reused five times. This technology demonstrates that the metal nodes of MOF materials can be used as active centers for catalytic reactions and exhibit excellent reactivity. However, the MOF materials used in this technology need to be prepared using terephthalic acid, which results in high costs. Furthermore, the aforementioned MOF catalysts require vacuum activation at 160-190℃ for 8 hours before being added to the reaction to achieve high reactivity, resulting in a long induction period.

[0005] CN117126196A discloses a PNP-Si ligand, its preparation method, catalytic system, and applications. This technology introduces alkylsilane into the catalyst ligand. The PNP-Si structure has large steric hindrance, which can ensure the stability of the ligand-chromium salt ratio and form a stable active center. This catalytic system can catalyze the oligomerization reaction of ethylene. However, the catalyst of this technology has a long residence time, a long induction period, and low selectivity for 1-butene.

[0006] Catalyst compositions for the dimerization of ethylene to 1-butene typically consist of transition metals, ligands, and alkylaluminum. Examples include IFP's ternary catalytic system (alkoxytitanium or aryloxytitanium with the general formula Ti(OR)4 or Ti(OR')4, aluminum compounds, and Lewis base additives) and SABIC's quaternary catalytic system (titanium ester with the general formula Ti(OR)4, ether modifiers, aluminoxanes, and other aluminum compounds). However, numerous studies have shown that ternary / quaternary catalytic systems require pre-complexation, and the presence of the complexation process prolongs the reaction induction period, affecting catalyst efficiency.

[0007] In summary, existing technologies suffer from problems such as high catalyst cost, long catalyst reaction induction period, or low 1-butene selectivity. Therefore, it is necessary to provide a new catalyst for the preparation of 1-butene from ethylene dimerization to improve these problems. Summary of the Invention

[0008] In order to solve the above-mentioned technical problems, the present invention aims to provide a catalyst composition and a method for preparing 1-butene. When the catalyst composition is used to prepare 1-butene by ethylene dimerization, it has a short reaction induction period, low cost and high selectivity for 1-butene.

[0009] The present invention provides a catalyst composition comprising an organotitanium compound and an organoaluminum compound; the organotitanium compound has the general formula Ti(OR1)2(OC2H4N(C2H4OH)2)2, wherein R1 is an alkyl group; the molar ratio of the organotitanium compound and the organoaluminum compound is 1:1 to 20.

[0010] The structural formulas of organotitanium compounds are shown below:

[0011]

[0012] Based on the modification of the steric hindrance and electronic environment of the catalyst's active center brought about by the aforementioned organotitanium compound structure, the subsequent use of this catalyst in the preparation of 1-butene from ethylene dimerization exhibits a shorter reaction induction period and higher 1-butene selectivity. Simultaneously, the catalyst cost is lower.

[0013] Furthermore, the molar ratio of organotitanium compounds to organoaluminum compounds is 1:1 to 5.

[0014] Further, R1 is a C1 to C4 alkyl group, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, or isobutyl. Preferably, R1 is methyl or isopropyl.

[0015] Further, the organoaluminum compound is selected from one or more combinations of R3Al, R2AlZ, and RAlZ2, where R3 is a C1-C4 hydrocarbon group, Z is -H, -F, -Cl, -B, -NH2, or -NHR, and R is a C1-C4 hydrocarbon group. Preferably, the organoaluminum compound is selected from triethylaluminum and / or triisobutylaluminum.

[0016] The present invention also provides a method for preparing 1-butene, comprising: mixing ethylene, the aforementioned catalyst composition and solvent to carry out a dimerization reaction to obtain 1-butene.

[0017] Further, the dimerization reaction temperature is 10–100°C; the dimerization reaction pressure is 1.0–5.0 MPa. Preferably, the dimerization reaction temperature is 50–60°C; the dimerization reaction pressure is 2.0–3.0 MPa.

[0018] Furthermore, the solvent is selected from one or more combinations of aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and unsaturated olefin solvents. Preferably, the solvent is selected from one or more combinations of butene, n-hexane, cyclohexane, heptane, octane, and decane.

[0019] In some alternative embodiments, the reactor used to carry out the dimerization reaction of the ethylene can be a batch reactor or a ring reactor, and the reactor is equipped with a stirring device, a heating device and a cooling device. The dimerization reaction can be carried out continuously or intermittently.

[0020] The traditional Alpha-Butol process requires a reaction time of more than 4 hours, while the present invention only requires a reaction time of 1 to 2 hours to release the full catalytic capacity of the catalyst. The reaction induction period is shorter, the catalyst is cheaper, and the selectivity for 1-butene is higher. Detailed Implementation

[0021] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0022] The structural formula of diisopropyl di(triethanolamine)titanate used in the examples is as follows:

[0023]

[0024] The structural formula of di(triethanolamine)titanate used in the examples is as follows:

[0025]

[0026] Example 1

[0027] This embodiment provides a method for the dimerization of ethylene with 1-butene, which includes the following steps:

[0028] After repeatedly evacuating and purging with ethylene three times in a 1-liter reactor, ethylene was introduced to atmospheric pressure, followed by the addition of 200 mL of n-hexane, 0.7 mL of triethylaluminum, and then 0.623 mL of diisopropyl di(triethanolamine)titanate (the molar ratio of diisopropyl di(triethanolamine)titanate to triethylaluminum was 1:3.7). The pressure was rapidly increased to 2.0 MPa, and the reaction was carried out at 50 °C for 40 min. After the reaction, the gaseous product was quantitatively collected using a wet gas flow meter and a gas collection bag, the liquid product was collected using a flask, and the solid product was collected using a sealed bag. The obtained products were analyzed and calculated. Gas chromatography analysis of the liquid product showed a selectivity of 84.69% for C4 and 15.31% for C6. The catalytic activity was calculated to be 0.75 × 10⁻⁶ based on the amount of ethylene consumed. 5 g / mol·h.

[0029] Example 2

[0030] This embodiment provides a method for the dimerization of ethylene with 1-butene, which includes the following steps:

[0031] After repeatedly evacuating and purging with ethylene three times in a 1-liter reactor, ethylene was introduced to atmospheric pressure, followed by the addition of 200 mL of n-hexane, 0.7 mL of triethylaluminum, and then 0.623 mL of diisopropyl di(triethanolamine)titanate (the molar ratio of diisopropyl di(triethanolamine)titanate to triethylaluminum was 1:3.7). The pressure was rapidly increased to 2.5 MPa, and the reaction was carried out at 50 °C for 40 min. After the reaction, the gaseous product was quantitatively collected using a wet gas flow meter and a gas collection bag, the liquid product was collected using a flask, and the solid product was collected using a sealed bag. The obtained products were analyzed and calculated. Gas chromatography analysis of the liquid product showed a selectivity of 90.35% for C4 and 9.65% for C6. The catalytic activity was calculated to be 0.87 × 10⁻⁶ based on the amount of ethylene consumed. 5 g / mol·h.

[0032] Example 3

[0033] This embodiment provides a method for the dimerization of ethylene with 1-butene, which includes the following steps:

[0034] After repeatedly evacuating and purging with ethylene three times in a 1-liter reactor, ethylene was introduced to atmospheric pressure, followed by the addition of 200 mL of n-hexane, 0.7 mL of triethylaluminum, and then 0.623 mL of diisopropyl di(triethanolamine)titanate (the molar ratio of diisopropyl di(triethanolamine)titanate to triethylaluminum was 1:3.7). The pressure was rapidly increased to 2.5 MPa, and the reaction was carried out at 50 °C for 60 min. After the reaction, the gaseous product was quantitatively collected using a wet gas flow meter and a gas collection bag, the liquid product was collected using a flask, and the solid product was collected using a sealed bag. The obtained products were analyzed and calculated. Gas chromatography analysis of the liquid product showed a selectivity of 90.68% for C4 and 9.32% for C6. The catalytic activity was calculated to be 0.75 × 10⁻⁶ based on the amount of ethylene consumed. 5 g / mol·h.

[0035] Example 4

[0036] This embodiment provides a method for the dimerization of ethylene with 1-butene, which includes the following steps:

[0037] After repeatedly evacuating and purging with ethylene three times in a 1-liter reactor, ethylene was introduced to atmospheric pressure, followed by the addition of 200 mL of n-hexane, 0.7 mL of triethylaluminum, and then 0.623 mL of diisopropyl di(triethanolamine)titanate (the molar ratio of diisopropyl di(triethanolamine)titanate to triethylaluminum was 1:3.7). The pressure was rapidly increased to 2.5 MPa, and the reaction was carried out at 50 °C for 90 min. After the reaction, the gaseous product was quantitatively collected using a wet gas flow meter and a gas collection bag, the liquid product was collected using a flask, and the solid product was collected using a sealed bag. The obtained products were analyzed and calculated. Gas chromatography analysis of the liquid product showed a selectivity of 83.66% for C4 and 16.34% for C6. The catalytic activity was calculated to be 0.63 × 10⁻⁶ based on the amount of ethylene consumed. 5 g / mol·h.

[0038] Example 5

[0039] This embodiment provides a method for the dimerization of ethylene with 1-butene, which includes the following steps:

[0040] After repeatedly evacuating and purging with ethylene three times in a 1-liter reactor, ethylene was introduced to atmospheric pressure, followed by the addition of 200 mL of n-hexane, 0.7 mL of triethylaluminum, and then 0.623 mL of diisopropyl di(triethanolamine)titanate (the molar ratio of diisopropyl di(triethanolamine)titanate to triethylaluminum was 1:3.7). The pressure was rapidly increased to 2.5 MPa, and the reaction was carried out at 60 °C for 40 min. After the reaction, the gaseous product was quantitatively collected using a wet gas flow meter and a gas collection bag, the liquid product was collected using a flask, and the solid product was collected using a sealed bag. The obtained products were analyzed and calculated. Gas chromatography analysis of the liquid product showed a selectivity of 83.64% for C4 and 16.36% for C6. The catalytic activity was calculated to be 0.74 × 10⁻⁶ based on the amount of ethylene consumed. 5 g / mol·h.

[0041] Example 6

[0042] This embodiment provides a method for the dimerization of ethylene with 1-butene, which includes the following steps:

[0043] After repeatedly evacuating and purging with ethylene three times in a 1-liter reactor, ethylene was introduced to atmospheric pressure, followed by the addition of 200 mL cyclohexane, 0.7 mL triethylaluminum, and then 0.623 mL di(triethanolamine)titanate (the molar ratio of di(triethanolamine)titanate to triethylaluminum was 1:1.5). The pressure was rapidly increased to 2.5 MPa, and the reaction was carried out at 50 °C for 40 min. After the reaction, the gaseous product was quantitatively collected using a wet gas flow meter and a gas collection bag, the liquid product was collected using a flask, and the solid product was collected using a sealed bag. The obtained products were analyzed and calculated. Gas chromatography analysis of the liquid product showed a selectivity of 86.21% for C4 and 13.79% for C6. The catalytic activity was calculated to be 0.67 × 10⁻⁶ based on the amount of ethylene consumed. 5 g / mol·h.

[0044] Comparative Example 1

[0045] This comparative example provides a method for the dimerization of ethylene with 1-butene, which includes the following steps:

[0046] After repeatedly evacuating and purging with ethylene three times in a 1-liter reactor, ethylene was introduced to atmospheric pressure, followed by the addition of 200 mL of n-hexane, 0.7 mL of triethylaluminum, and then 0.623 mL of tetrabutyl titanate (molar ratio of tetrabutyl titanate to triethylaluminum was 1:2.85). The pressure was rapidly increased to 2.5 MPa, and the reaction was carried out at 50 °C for 40 min. After the reaction, the gaseous product was quantitatively collected using a wet gas flow meter and a gas collection bag, the liquid product was collected using a flask, and the solid product was collected using a sealed bag. The obtained products were analyzed and calculated. Gas chromatography analysis of the liquid product showed a selectivity of 79.62% for C4 and 20.38% for C6. The catalytic activity was calculated to be 0.62 × 10⁻⁶ based on the amount of ethylene consumed. 5 g / mol·h.

[0047] The test data from the examples and comparative examples are shown in Table 1.

[0048] Table 1

[0049]

[0050] When the catalyst composition of the present invention is used for the preparation of 1-butene by ethylene dimerization, the reaction induction period is short and the 1-butene selectivity is high.

Claims

1. A catalyst composition, wherein, It includes organotitanium compounds and organoaluminum compounds; the general formula of the organotitanium compound is Ti(OR1)2(OC2H4N(C2H4OH)2)2, where R1 is an alkyl group; the molar ratio of the organotitanium compound to the organoaluminum compound is 1:1 to 20.

2. The catalyst composition according to claim 1, wherein, R1 is a C1 to C4 alkyl group.

3. The catalyst composition according to claim 1, wherein, The molar ratio of the organotitanium compound to the organoaluminum compound is 1:1 to 5.

4. The catalyst composition according to claim 1, wherein, The organoaluminum compound is selected from one or more combinations of R3Al, R2AlZ and R3AlZ2, where R3 is a C1 to C4 hydrocarbon group, Z is -H, -F, -Cl, -B, -NH2 or -NHR, and R is a C1 to C4 hydrocarbon group.

5. The catalyst composition according to claim 1, wherein, The organoaluminum compound is selected from triethylaluminum and / or triisobutylaluminum.

6. A method for preparing 1-butene, wherein, include: Ethylene, the catalyst composition according to any one of claims 1 to 5, and a solvent are mixed to carry out a dimerization reaction to obtain 1-butene.

7. The method for preparing 1-butene according to claim 6, wherein, The dimerization reaction is carried out at a temperature of 10–100°C and a pressure of 1.0–5.0 MPa.

8. The method for preparing 1-butene according to claim 6, wherein, The dimerization reaction is carried out at a temperature of 50–60°C and a pressure of 2.0–3.0 MPa.

9. The method for preparing 1-butene according to claim 6, wherein, The solvent is selected from one or a combination of two or more of aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and unsaturated olefin solvents.

10. The method for preparing 1-butene according to claim 6, wherein, The solvent is selected from one or more of butene, n-hexane, cyclohexane, heptane, octane, and decane.

Images